1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus such as an etcher or a CVD (Chemical Vapor Deposition) that controls the flow rate of gas for manufacturing semiconductor devices, and specifically, to a semiconductor manufacturing apparatus performing an automatic inspection and an automatic switching of flow rate controllers, flow rate indicators and the like.
2. Description of the Background Art
Recently, semiconductor devices are applied in apparatuses of every field with enormous consumption amount. Among manufacturing apparatuses for such semiconductor devices, apparatuses such as an etcher or a CVD utilizes various gases for processing. Generally, for a manufacturing apparatus that uses the gas for processing, a mass flow controller (MFC) controlling the flow rate of the gas, a mass flowmeter (MFM) for inspection that indicates the flow rate of the gas and the like are used.
Some techniques related to such a semiconductor manufacturing apparatus are inventions disclosed in Japanese Patent Laying-Open Nos. 6-53103 and 5-108167.
A semiconductor manufacturing apparatus disclosed in Japanese Patent Laying-Open No. 6-53103 includes one or more calibrating mass flow controller(s) for automatically calibrating the flow characteristics of a mass flow controller, and a piping system serially connecting the measuring mass flow controller and the calibrating mass flow controller(s), through which less reactive gas is passed.
In a control apparatus disclosed in Japanese Patent Laying-Open No. 5-108167, a sequence controller monitors the fluctuation in an operation of a mass flow controller for a predetermined period from the initiation of the operation, thereby detecting an anomaly in the mass flow controller.
As described above, the semiconductor manufacturing apparatus disclosed in Japanese Patent Laying-Open No. 6-53103 includes the piping system serially connecting the measuring mass flow controller and the calibrating mass flow controller(s), which enables calibration of the measuring mass flow controller to be inspected. On the other hand, since the flow rate of the gas is controlled by the calibrating mass flow controller(s) first, and then the gas is passed to the measuring mass flow controller to be inspected, only the flow rate sensor unit of the measuring mass flow controller can be inspected, while the flow rate control performance thereof is left unchecked.
Further, since the gas for inspection flows into the calibrating mass flow controller via an exclusive path, a complicated piping system will be required, which involves additional costs for parts and piping, making the semiconductor manufacturing apparatus undesirably expensive.
Still further, as described above, in the control apparatus disclosed in Japanese Patent Laying-Open No. 5-108167, the sequence controller detects an anomaly in the mass flow controller. On the other hand, when an anomaly is found, it is required to stop the operation of the semiconductor manufacturing apparatus, to remove the piping, to change the mass flow controller, and thereafter to perform tests such as a leakage test or a process test. Therefore, the semiconductor manufacturing apparatus must be stopped for extremely long period undesirably.